My tutor has asked me to use manual, because he wants me to learn to expose correctly. That's the point of the excersize, it doesn't really matter if the photo is interesting or creative just so long as they are correctly exposed.
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Exposure - Exposed!
If your tutor is telling you to use manual, because he wants you to expose 'properly' he darn well aught to know there is NO such thing as a 'proper exposure'.. your first instinct to reject the exposure your camera offered you was correct, the 'best' exposure is the one you like best.. what the camera suggests as the best settings to get an exposure it thinks likely you'll think best based on its metering are just that 'suggestions'.. now there's a lot of expert know-how gone into the programming of your camera for it to measure the light levels coming through the lens and to make calculations based on that, to decide what settings are likely to work well for them... AND with a computer brain the size of a small planet and umpety hundreds of expert photographers knowledge polled and compressed into its coding, it's 'suggestions' on whichever mode you make are probably pretty darn close most of the time..
Switching to fully manual, making your own ISO, Shutter and aperture settings, based on nothing more than the exposure indicator in the view-finder... well, at BEST you are likely to do no more than pick the exact same, or similar enough ISO, Shutter and Aperture settings, as the camera would on an 'auto' mode, and it will make bog all odds to either the exposure or how 'good' the photo may be.... at worst... you get make settings that are utterly inappropriate for your subject, and you get a hoolie.... 'cos you dont know as well as the camera what the different settings are doing for you...
But in ANY case, being a slave to the meter.. whether its the Through-The-Lens (TTL) meter in the camera, or an independent hand held meter, whatever the 'exposure mode', be that simple 'spot-reading' taking just one very small light level sample from a tiny bit of your scene, or a wider centre-weighted average, taking a much bigger 'sample' to base the EV on, or a complicated 'multi-spot' calculation, averaging lots and lots of tiny point samples, in what might be described as 'Matrix' or 'Evaluative' metering modes.... OR with a hand held meter, you take a 'reflected' light meter reading, of light reflected off your subject, or an incident reading of the ambient light falling on the entire scene, or even a 'flash' reading from a flash-lighting set up... end of the day, ALL the meter, is doing is making a 'best guess' of an Exposure Value likely to get you a pleasant exposure..
Doesn't matter ONE JOT how sophisticated the meter is, how many samples it makes, or what mathematical acrobatics it performs on the numbers, or how accurate it claims to be... its doing ONE thing, suggesting a SINGLE exposure value.. that is probable 'good' to make an averagely 'bright' photo.... and there is NOTHING to say that it is going to be even 'mathematically' correct, let alone scientifically perfect and even LESS, the exposure YOU find most pleasant!
You might have up to three stops worth of alternative 'Exposure Values' either side of what the meter suggests, that could all make an acceptable exposure, and one of them might be more or less pleasant, but following that indicator's suggestion in the view-finder or the number offered on a hand held meter.... is only ONE suggestion of possible Exposure value.... you do not have to take it! It is NOT always going to be the 'best' exposure value, and it is NEVER going to be the 'perfect' exposure value, as there is no such thing!
I'm currently doing an assignment for my photography course, where my tutor wants me to take a photo of a person or something of similar size, 2 metres distant with a background that isn't plain. I then have to set my exposure to its widest (f/4.5) and match the shutter speed, then stop down the aperture and decrease s/s simultaneously and describe the effect on the photo (I.E depth of field, noise, sharpness, colour saturation.).
OK.. so down to business... dealing with teachers, 101, the clue is in the question... what are they trying to get you to prove?
What do the books say should change with the aperture?.. exposure... which he's told you to keep the same, by compensating with the shutter speed... and the Depth of Field... how much in front and behind your focus point is in 'sharp-focus'... did he explicitly ask you to comment on noise, saturation and sharpness? What influences them. Do your home-work, before you do THE home-work!
Noise is a function of ISO... and you tend to only get it at higher ISO settings, and even then, it tends t not be particularly obvious unless you are shooting in low light, and still more, you display your picture at a large enough scale to actually see it! My daughter's GCSE assignments all called for a 'contact sheet' from each assignment shoot, 16 frames, to an A4 page, each frame barely the size of an old 35mm film negative, 24x36mm... you do NOT 'see' noise in a photo that small! You wont see it on a full A4 photo, from a DSLR with over perhaps 16Mpix resolution when it's been shrunk to fit the page! You will likely only see 'obvious' noise if you display at 1:1 pixel resolution, at a large scale; so a sectional crop from your photo at A4 or on a monitor 'zoomed in' to pixel res.... and even THEN... if you want to 'show' obvious 'noise' you had better have made sure you have turned the in camera noise reduction processing 'off'.....
Sharpness... a modern obsession that's a function of the popular imagination, more than anything,
I think.. invert it to 'softness' and by association you get 'soft focus'..which tends to 'out of focus' as you go through the Depth of Field about the critical focus point.... so there is some correlation between perceived sharpness and aperture, for any given lens, and you have been told to use the same lens, so this is possibly what your teacher may want you to consider... or see how you consider, and or explain.. other wise it tends to be a facet people consider between the way different lenses render an image, and aberrations they have across the frame.... most often though I think a lot of what many perceive as 'sharpness' is a more clinical contrast rendering of the 'focus-fade' through the DoF zone, and across the contrast colour range of the scene.. more dependent on in camera and post processing of the image as anything; & I seriously doubt your teacher expects you to get that 'geeky' as a newby, though...
Colour Saturation? How deep or vibrant colours are reproduced. Biggest influence on that to any image, starts with the original scee, ad whether the actual colours are particularly strong or vibrant to begin with! A polarizing filter, will tend to saturate colour, but no mention of one in your assignment brief, and if there was, or it was the intent, you'd be told to show how a polariser saturates colour, with comparison shots with and without. Only other things that might effect colour saturation is the exposure; under-exposure tends to saturate colour a little, over-exposure tends to wash it out.. but again, you have been told to keep the exposure the same, so presumably you should be expected to note no change in saturation for your assignment set.
Back to teachers 101... IF they expect you to comment on something in your report..... means they expect you to know what it is, and if they haven't told you what that is... THAT is the assignment FIND OUT Not just follow the instructions on the packet... read between the lines!
So, he wants you to take a set of shots of a subject 2m from the camera, all at the same exposure, but with different apertures from your widest f4.5 up.. balanced on the shutter speed... which implies keeping the ISO constant... don't say so, but implies.... For the same subject and 'stage' and at the same exposure, and without adding a filter, or changing lenses... doing your home-work and back-ground reading then, ALL you should really be looking at is the effect of shutter and aperture..... so what do each of them do?
Shutter Speed - freezes motion. Anything that moves during the exposure period, will blur in the frame. So shorter exposure periods.. faster shutter speeds (see next Tutorial if I ever get round to it WHY shutter speed is a bit of a misnomer, and 'exposure period' better describes what we are worried about with the Shutter Speed settings!) Faster Shutter less time anything has to move in so the less blur you will get from any amount of camera shake of subject movement.
No hint in the brief he wants you to use a moving subject. so he isn't expecting this to be demonstrated, and if you use a tripod and a static subject you wont see any effect cos nothing will move! so do so! Remember, Keep-It-Simple-Stupid.. DON'T make something you have to explain, unless they ask for it, or assignment implies its asked for!
And THAT is starting to 'Plan the Shoot' for the assignment.. and how to do it to succinctly full-fill the brief and answer both what has bee asked and implied....And leaves it essentially a very simple demonstration of the change n Depth of Feild with aperture... which was also hinted at in the brief by the 'background that isn't plain'... he wants something in the back-ground to actually go out of focus as you open up the aperture.....
So the REAL assignment is to show THAT... and sorry by I haven't got round to either tutorial idea I have for them, on Aperture and Depth of Focus, and taking that a bit further, on Shallow-Focus vs 'Selective-Focus'... you may have to do a bit more back-ground reading and home-work on these; but for now... Depth of Focus is proportional to the ratio of the camera to subject distance, as well as the aperture... wider the aperture less DoF you get around your focus point, closer your focus point, less DoF you get.... and you have a prescribed focus distance of 2m.... so to get a very shallow DoF you cant get up close, you have to use a wider aperture... and you don't have a particularly wide one, at f4.5.... so to actually get the back-ground well out of focus, even at your widest aperture, you will need to move that well behind your subject.....
This gives you more clues to plan the shoot... you need a BIG space to get the back-ground well away from the subject.... hints at an out-door shot where you have plenty of open space... a play-groud or park or something... but you need 'things' in that back-ground to come into focus as you start stopping down the aperture... a green field or bit of tarmac isn't going to give you much out of focus detail to see in the fuzz.. neither would a plain wall, like a building... so think about it.. you want to show the effect, you don't just want ONE back-ground... Topic is Depth of Field.... you would show the Depth of Field much better if you have some 'depth' to your back-ground... layers of back-ground that as you stop down are 'revealed' in each shot...
Trusty old Ziess 50 on my film camera is conveniently to hand, and has DoF marks on its focus scale... handy old innovation that... but, setting focus to 2m..
@ f4, I have a DoF of not a lot... almost nothing on the scale, maybe only 2-3cm around my focus point.
@f8, @f11, still pretty slim, maybe double, but 8-10com around the subject distance still ent much.
@f11,, getting a bit closer to the next numbers on the focus scale, 'almost' but not quite1.9m in front of the focus point, to almost 2.2m behind, about 30com total
@f16, we have a bit more DoF, almost 1.75m infront of the subject, to about 2.25m behind
@f22, its down to about 1.7m infront and up to almost 2.5m behind...
Might be a little bit different for your lens, I don't know what focal length it is or you are using it at f a zoom.... BUT thats the sort of DoF range we are in, and eed to show studd in and out of focus for the assignment...
So, Planning the the shoot; you need a subject, preferably one that wont move,, and in first wide-open shot, at 2m, you are goig to get about 2-3cm of Dof.. so that about how 'deep' you want your subject to be to show it/them all nicely 'i focus'.. what can you use abut that big. A person? Focus on their eyes, and a full size person has about 5" between nose and ears.. that's more than double the 5cm Dof you are likely to have.... suitable subject? Know any-one smaller? Who can sit still long enough? Could work, and first shot showing deliberate shallow focus, tip of the nose and ears going oof around the eyes... people like photos of other people... could be worth a go... second shot with around 10cm of DofF would probably get nose and ears more fully in the DoF zone to show quickly a DoF difference, and some 'depth' whilst the back-ground is still clearly oof. Tighten up some more.. next shot, you'll have about 30cm of Dof.... aught to be more than enough to get a head nicely in focus.. but anything further behind is likely to still be pretty soft..... but you would like to have that 'back-ground getting inside teh DoF zone, before you run out of tighter apertures! Can your lens stop down to F22 or more? Because at that end, you are still pretty 'shallow' at this close a focus distance, and anything more than 2.5m behind is not going to come into the DoF zone, where even at the far limit, it is only 'acceptable' sharp focus, not exact sharp focus....
So, what can you set up? Local play-ground? Something like that, where you could maybe sit a willing (r uwilling!) sucker.. sorry I mean 'model' on maybe a park bench, within 2m of a bit of play equipment, maybe a colourful climbing frame or something?
Nearest bit of play equipment would be oof in your early wide aperture shots, and creep in to focus as you stop down; play equipment behind that, perhaps the park fence or hedge further behind that still, at even greater range, staying out of the DoF zone of acceptable sharpness, but being resolves more sharply in the wider aperture shots of the set. Colourful playground equipment if you can get it, to give you some strong colour, in the shot to consider those questions of saturation, if you really have to. Or smething 'like' that maybe.
But NOW, the question has answered your assignment for you, and you know how you need to set the shoot up, and what's likely to work, and having done THE home-work before your home-work, you aught to have a pretty good idea what to expect, and what your report is going to say!
Shots show that as the Aperture is closed down.... the Depth of Focus increases... at wide apertures the back-ground is almost entirely out of focus, and even some of the model isn't very sharp.. as you stop down, most of the back ground stays blurry, but more of the model comes into focus or at least sharper, until at very small apertures, a lot more closer back ground is becoming sharp and even far background less blury... Using a tripod, and a model sat and not moving, with shutter speeds all above (whatever) the effect of reducing shutter speed to maintain the same exposure, has not resulted in any noticeable motion blur. In good day-light and at moderate ISO (whatever) circumstances that might create noticeable noise (high ISO & low-Light) have been avoided, and none is obvious in any of the shots. .(This is almost doing t all for you.... ) Where the bright coloured (whatever) seen (wherever it is in the shot) is i sharp or acceptably sharp focus..... (I'll leave you to guess at the aswer to that oe, and see whether you are rght when you have take the pics.. cant do it ALL for you ;-))
But that's the task here... inferring what the real question is and what's expected of you from what's in the question; reading between the lines, and dong the home-work behind the home-work to PLAN the shoot to answer the question...
And it is essentially a simple demo of the effect of the aperture control... ad the assignment written to give you a reasonably good chance of seeing it, the 2m focus distance 'critical' bringing the DoF range down into a range its likely to be pretty thin, even with moderately slow fastest apertures.
And with that degree of focus criticality enforced.. I would strongly recommend, you DO use a tripod to keep the camera subject-distance as close as possible between shots; I would ALSO suggest you turn 'off' the Auto-Focus.. and if you use a person as your model, who may move a bit between them.. focus manually on their eyes for the 1st shot.. then rather than re-focusing for each successive one... you ask the model to lean forwards or back in the seat to get the same 'pose' and bring their eyes back to that same focus point to precisely maintain that focus distance between shots.
And don't get hung up on exposure! or correct exposure! You are using manual, NOT to show you are smarter than the camera but simply so that you can, in this case, set different apertures to show the effect it has on a photo, and keep all else constant, without the camera making 'other' changes between shots.. THAT is why you (should) be on manual, NOT to get a proper exposure... cos there's no such thing!
Hope That Helps
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